This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Saliva is an oral fluid rich in over a thousand unique proteins which are secreted by several pathways, possibly including exosomes. Exosomes are membrane-bound vesicles of endosomal origin within multivesicular endosomes that are constitutively secreted. A mass spectrometry-based shotgun proteomics approach was employed to explore the possibility that many of the proteins found in saliva are derived from exosomes. Using MudPIT (multidimensional protein identification technology), we catalogued 491 proteins in the exosome fraction of human parotid saliva. Parotid glands secrete exosomes that may carry informative protein markers useful in the diagnosis, prognosis and treatment of oral and systemic diseases.